Manufacture of decolorizing or activated carbon



July 18, 1933. T. A. GOSKAR 1,918,467 J MANUFACTURE OF DECOLORIZING ORACTIVATED CARBON Filed Fe b. 14, 1950 2 Sheets-Sheet 1 July 18, 1933. T.A. GOSKAR 1,918,467

MANUFACTURE; OF DECOLORIZING OR ACTIVATED CARBON Filed Feb. 14. 1930 2Sheets-Sheet 2 T 720177116 119 G04? r v 40 desirably carbonmodifications,

Patented July 18, 1933 rxonaslauausrus aosma, or nua'nnm-on-saal anqnannMANUFACTURE or nnoonomzms on. ACTIVATED Cannon Application m d a yalNo.428,403,11116in'GreatBritain February" 19, 1929f This inventionrelates to improvements in the methods and apparatus employed in themanufacture of decolorizing or activated carbon, which is a carbon of ahigh degree of purity and capacity for adsorbing and/or absorbing gasesand coloring matter. These qualities are impaired by treating carbon atelevated temperatures with various activating substances appli d l. lyin gaseous form.

The known processes for the production of activated carbon comprise inthe main at least two stages in the first of which carbonaceousmaterials of either vegetable or mineral origin such as peat, lignite,brown coal or coal are subjected to distillation and carbonization. Inthe second stage which immediately succeeds the first, the carbon-'-ized residue is treated at high temperatures with the activatingsubstance, for example super-heated steam, or other vapors or gases -ormixtures thereof.

In order to ensure a high yield of activated carbon of good quality itis essential that ;the mass of .material in the retort should be keptsufliciently open or orous to allow easy and rapid percolation o gaseswhether evolved in the distilling and carbonizing stage or added for thepurpose of activation; It is also desirable, that the fragments ofmaterial should themselves possess some porosity to allow permeation 2fthe activating gases to the core of each ra and the operationis carriedout with care particularly as regards the temperatures ob-' tainin'g inthe various stagesfof'the operation a very pure product'is obtainedwhich containslittle or nographitio or other" un- The preliminarypreparatifl n of thejg'raw material; is therefore of the utmostimportance and has an effect in every stage ofthe operation.

Primarily accordingzito the present inventionzl prepare the raw materialin such a manner as to ensure approximate 11111? formity in composition,textureand dimensions. Preferably ;.it is formed into small lumps orpellets of suitable size and density ent. If these'conditions areassuredby mixing the raw material'such as peat or mixtures of peat and othercarbonaceous materials in a moist condition in ugging' ormaceratingmachines of any wel -known or suitable type designed for breaking'upsoft 1 fibrous materials, and then extrudin the mixture and cutting itto the desire size which may forinstance be about one quarter inch toone half inch in. diameter and length. Alternatively the moistmaterialmay be pressed or molded to'the desired size and shape. Thetexture and density of the pellets may be controlled byvarying themoisture content of the mixture, and I have found from 40% to moistureto be very effective during the mixing operation. I

After the pellets have been formed by extrusion or molding or othewisethey are .dried in the upper zones of an apparatus comprising a verticalor inclined chamber or series of chambers through which thematerialflows by gravity and in which the succeeding operations arecarried out.I prefer to reduce the moisture content to" 20% or less before thepellets proceed to the carbonizing stage and this may convenient- 'lbe'done byjcausingthe pellets to flow t rough a relatively long dryingchamber of their length are louvered or reticulated to allow the passageof drying gases across the mass of moist pellets. I a

This *relatively deep bed of moist mate rial constitutes a feature of:the present in} vention in that j a sufiicient seal is thereby formed atthe feeding end of the apparatus to eliminatethe need for mechanicallyoperatedfeed valves,"the dee bed of moist material offering a highresistance to the infiow' of air from the atmosphere which might.otherwise take place under the suction employed to draw the drying gasesacross the mass of-material. v j

* After drying, the pellets pass freely into a carbonizing retort at'thelOWBl'BIlCl-OfWhiOh is the activating chamber. The necessary heat forcarbonization is preferablysupplied' by direct contact of the highlyheated ases u from the activating zone,whichare'oaused the gases ev .topcrcolate upwards throughthe dry A llets, picking u and carryin ofi witht em oli'ed by disti ation. As the temggrature progressively increasesfrom the ginning to the end of the carbonizing zone,.t e gases andvapors are given off at their several volatilization temperatures, and,passing steadily upwards, are.in no case subjected to hi hertemperatures which would tend to crac them. The gases and vagors arethen withdrawn. from the upper en of the carbonizing zone. This internalheating by percolation of hot gases through the porous bed of pelletswhich are themselvesof porous texture produces a very even heatingthroughout the bed of material and revents the formation of graphitic orot er undesirable carbon modifications.

The charred pellets from the carbonization stage are next stronglyheated to in'- candescence and subjected to the well-known action oftheactivating gases which may be steam, air, carbon dioxide, carbonmonoxide or hydrogen or suitable non-explosive mixtures of these gasesor vapors.

According to my invention I can carry out these processes of drying,preliminarycarbonization, and activating in separate apparatus, but inorder to ensure regularity of operation and economy I prefer to arrangethe separate apparatus in vertical sequence, and thereby formsubstantially one continuous chamber. a

One form of apparatus in accordance with the resent invention andspecifically ada ted or carrying out the processor this 1nvention isillustrated in the accompanying drawings, of which Fig. 1 is a vertlcalsectibn of the series of chambers in .whichthe pelleted material istreated, the associated apparatus a being shown in elevation;

Fig. -2 is a sectional elevation at right angles to Fig. 1. v v sReferring to the drawings A indicates diagrammatically a pugging ormacerating machine of any convenient type into whlch peat or saw dust,or peat and other carbonaceous material or saw dust andothercarbonaceous material is fed and from which it is discharged in the formof small pellets of about inch to inch in diameter and length. Thematerial fed to the machine is in a moist state, containing preferably40% to moisture, and after thorough pugging is extruded through a die--plate and cut up by a rotating knife (not shown) into pellets'of thedesired size.

These pellets, still in a moist condition, are discharged directly intothe open end of a chamber B of substantial depth and of greater lengththan breadth in horizontal cross section, wherein they form, due totheir moist condition, an effective seal against the passage ofatmospheric air vided with louvered or reticulated walls B and B, thelouvers in one case bein horizontally, and in the other case vertic y,are

pro nets of combustion are supplied by a pipe 0 controlled by a valve 0om a combustion chamber to be hereinafter described. The hot gases aresucked by a fan D' through the mass of pellets between the walls B and Bsubstantially reducing their moisture iii lltsf db t m h f epe e ee ygrav1 roug a urther drying zone E, which is heated. by hot gases andvapors rising through a chamber F from acarbonizingretort G whichimmediatel succeeds the chamber E, the pellets passmg freely from theopen lower ,end of the latter into the retort. At the commencement ofthe carbonizing stage the ;moisture content of the pelletshas'preferably been reduced to about 20% and the pellets are heated andfinally carbonized by direct contact with hot gases drawn b a fan J froma combustion chamber H an caused to pass upwards through the mass in theretort G. The temperature gradually increases from the beginning to theend of the carbonizing stage and due to the upward movement of thegases. through. the mass of material the various gases and vapors whichare distilled ofi at their several volatilization temperatures are notsubjected ranged; To this part of the chamber hot in their passageupwards to higher temperatures which would tend to crack them.

The hot gases and oil vapors'are drawn through the chamber F, and ductsE pass ing across the chamber E, the gases serving in their passage todry the pellets descending the chamber E, and are led bya pige Kprovided with a valve K to a con enser L, where the condensibleconstituents, are removed and .the stripped gas delivered throughpipes'M- and N to the cgmbustion chamber H, where they are burnt tosupply a the heat for activation of the carbonized pellets which aredelivered from the'retort G into an activatin chamber 0 maintained at atemperature 0 about 900- to 1200 C.

A feature of this invention consists in supplying the activatingagent'in liquid form so that the quantity may be accurately controlledto produce the desired activating chamber Superheated steam is asatisfactory activating agent and accordingly water maybe delivered froma sight eed regulator P pressure in the through a pipe P to a number ofarches or inverted V-sh'a ed channels "P passing across the cham er. C.-The water by passage through the combustion'chamber H is converted intosteam which is superheated by. contact with .the incandescent mass ofpellets "and .this su erheated steam rises evenly through'the ody ofllets in the chamer O. Thiseven distri ution of the activating agentisof great importance and is due largely to the fact that the activatingliquid also enables the pressure in the activating chamber to besimilarly controlled,

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and I have found it advantageous to use a pressure lower than thoseemployed in processes hitherto proposed.

A suitable pressure is measured by a three inch column of water, andthis ensures a rel atively slow movement of the activating agent throughthe body of pellets,- allowing ample time for it thoroughly to permeatethe pellets. In the process of activation in the chamber 0, combustiblegas is produced which makes its way partly into the combustion chamber Hwhere it is burnt, and is partly drawn up throu h the retort G, theproportions so dealt wit being regulated by the valves C and K I Thecombustion chamber H is provided with valve-controlled openings Q forthe admission of atmospheric air to support com bustion of the gases insaid chamber.

The activating chamber 0 is surrounded at its lower end by a waterjacket R which serves to cool the material before it is delivered to theatmosphere by means of a pair of rotating valves S, which take thematerial from both sides of the retort and ensure an even downwardpassage of the pellets through the activating chamber 0. These rotatingvalves consist preferabl of rotatable drums having peripheral poo ets,the capacity of which is made variable-for instance, by means ofadjustable false hot The water jacket R also surrounds the valve casingsand keeps them cool.

As illustrated in Fig. 2 a gas producer T may be connected with thecombustion chamber H to furnish a supply of gas for starting up theapparatus, after which the process .is in -most cases self-supporting, a

, suflicient supply of gas for the heat requirements of the processusually being obtained from the distillation and carbonization' of thepelletedraw material.

\Vhat I claim is 1-- 1. A rocess for the manufacture of activated carbonconsisting successively in macerating non-distilled carbonaceousmaterial with from 40 to percent by weight of'water but with nosubstantial proportion of binding agents, subjecting said material at alow pressure to a forming operation (e.g. extrusion, moulding) for theproduction of pellets of substantially uniform size between one-quarterand one-half inch in diameter and of substantially uniform compositionand texture, chargmg'sa'id pellets into a substantiallyuprightchamber soas substantially to fill the'upperpart of said chamber, drying-saidpellets by passing hot gases therethrough, subjecting said pellets todrydistillation by direct contact with the gases from a subsequentactivating stage and finally heating the carbonized pellets and treatingthem with an activating agent. i i i 2. A rocess for the manufacture ofactivated carbon consisting successively in macerating non-distilledcarbonaceous material with from 40 to 70 percent by weight of water butwith no substantial proport on of binding agents, subjecting saidmaterial at a low pressure to a forming operation (e.g. extrusion,moulding) for the production of pellets of substantially uniform sizebetween one-quarter and one-half inch in diameter andof substantialluniform composition and texture, chargmg said pellets into asubstantially upright chamber so as substantially to fill the upper partof said chamber, drying said pellets by passing hot gases therethroughuntil their moisture content is reduced to not more than 20 percent,subjecting said pellets todr'y distillation by direct contact with'thegases from the direct activating stage and finally heating thecarbonized pellets and treating them with an activating agent.

3. A continuous rocess for the manufacture of activated carbonconsisting successively in macerating non-distilled carbonaceousmaterial with from 40 to70 percent by weight of water but with nosubstantial proportion of binding agents, subjecting said material at alow pressure to a forming operation (e.g. extrusion, moulding) for theproduction of pellets of substantially uniform size between one-quarterand one-half inch in diameter and of substantially uniform compositionand texture, charging said pellets into the upper end of a substantiallyupright drying chamber so as substantially to fill said drying chamber,dryingsaid pellets by passing hot gases through the lower part at leastof said chamber,

passing said pellets downwardly by gravity into a retort communicatingfreely with the lower end of said'drying chamber for dry distillation bydirect contact with the gases from a subsequent activating stage andfinall passing the carbonized pellets downward y by gravity into anactivating chamber communicating freely with the.

lower end of said retort for heating and treatment with an activatinagent.

4. A process for the manu acture of activated carbon consistingsuccessively in macerating non-distilled carbonaceous mate rial withfrom 40to 70 percent by weight of water but with no, substantialproportion of dryin distillation by direct contact with the gases from asubsequent activating finally heating the carbonize pellets and treatingthem with an activating agent art at least of which is supplied inliquid orm for subse uent evaporatlon, the supply of said 1i uid ingregulated to produce a pressure pound per square inch aboveatmosphericin the activating stage.

THOMAS AUGUSTUS GOSKAR,

stage and etween atmospheric and one

